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This invention relates to fitting a wire harness inside a section of drill pipe that is used to form at least a portion of a drill string for drilling oil, gas, and geothermal wells. More particularly, this invention relates to a wire harness capable of transmitting power and data through the drill pipe. The harness may be connected to sensors and transducers in drilling tools, such as drill bits, mud motors, reamers, or MWD devices so that the data and power may be transmitted along the drill string to and from the surface during the drilling operation.
The following patents describe various attempts to transmit data and power along the drill string. To date none of these proposals have achieved commercial implementation due in part to their complexity, expense, and incompatibility with traditional drill pipe design and manufacturing methods as well as to maintenance procedures for the pipe joints.
U.S. Pat. No. 3,696,332, incorporated herein by this reference, teaches a direct contact means for transmitting power across the mating tool joint. The invention discloses the use of insulated conductor segments, ring shaped metal connectors, and a resilient biasing means located in the pipe joints. The electrical connectors contain a generally ring-shaped and substantially full circle contact-making conductive metal portion that is: located within a annular groove within a pipe joint element; electrically insulated from the groove walls; and is electrically connected to an insulated conductor.
U.S. Pat. No. 4,445,734, incorporated herein by this reference, teaches the use of an insulated wire segment located within a liner and direct electrical contacts. Two types of contacts are disclosed and are mounted so that when the drill pipe is screwed together, the sides of the contacts contact one another to make the connection. A flexible and a rigid ring are employed in the joint. The flexible ring is urged towards the rigid ring by means of a pressure conduit in communication with the drilling fluid. The insulator for the rings features a wiping mechanism so that as the rings come together, contaminants that would otherwise impede the connection are wiped away.
U.S. Pat. No. 4,220,381, incorporated herein by this reference, teaches the use of electrodes exposed to the drilling fluid to make the connection across the joint. The electrodes are connected to conductors that are shielded by an aluminum or plastic drill pipe liner, or a conduit sprung against the walls of the pipe bore.
U.S. Pat. No. 4,884,071, incorporated herein by this reference, teaches the use of a Hall Effect coupling transmitter/receiver as a means for bridging the drill pipe joint. Data is produced downhole by sensors located along the drill string or in downhole tools. The sensors are provided with a power supply for transducing the data and sending it to the pipe joint where it is received by a Hall Effect coupling transmitter. The data is then received by a Hall Effect received across the joint and forwarded through conductors up the drill string to the surface. The conductors are protected from damage by being inserted into conduits sprung against the side of the pipe bore.
Those skilled in the art are also referred to U.S. Pat. Nos. 6,041,784 and 6,057,784, incorporated herein by these references, for additional proposals for transmitting a data signal along the drill string.
What is needed is a wire harness for conveying power and data along the drill pipe that is simple in design, inexpensive, reliable, and non-intrusive to contemporary field usage.
This invention presents a drill pipe wire harness for transmitting power and data along the length of a section of drill pipe and, accordingly, the entire length of the drill string. The wire harness is particularly useful in electromagnetic inductive coupler applications, but it may also be adapted to other non-contact systems such as a Hall-Effect coupler, as well as direct and indirect contact connections. The harness consists of two rings joined by one or more insulated conductors. Alternatively, it may consist of a ring connected to one or more sensors by one or more insulated conductors. The rings are positioned within the tool joints of the drill pipe and the insulated conductors are strung along the inside bore wall of the pipe. The conductors may be cemented into grooves formed in the bore wall; they may be shielded by, or woven into, a pipe liner; or they may be housed in conduits within the bore of the pipe. In this manner, they may be protected from abrasive drilling fluid and tools passed through the bore of the pipe during the drilling operation. Each ring is provided with a means for connecting the conductors to a means for transmitting power and data. It is also contemplated that either or both rings may comprise the means for transmitting power and data.